With recent developments in electronics technology, monolithic ceramic capacitors have rapidly decreased in size and increased in capacity.
A monolithic ceramic capacitor is fabricated by alternately stacking dielectric layers and internal electrodes to form a laminate and sintering the resulting laminate. In order to decrease the size and increase the capacity of a monolithic ceramic capacitor, it is necessary to reduce the thickness of each dielectric layer.
However, when dielectric layers are thinned, voltage of a high field strength is applied to the dielectric layers. Therefore, a decrease in the relative dielectric constant εr, a deterioration in the temperature characteristic, and a decrease in reliability may be induced.
Consequently, the dielectric ceramic has been required to be able to retain a high dielectric constant even if a high field strength voltage is applied to the dielectric layers due to a decrease in the thickness thereof, and to have excellent reliability achieving a good isolating property, dielectric strength and endurance.
According to such requirements, a dielectric ceramic containing 0.2 to 5.0 parts by weight of a certain sintering additive per 100 parts by weight of a main component represented by general formula {Ba1-xCaxO}mTiO2+αRe2O3+βMgO+γMnO (where Re represents a specific rare-earth element) has been disclosed (Patent Document 1).
In Patent Document 1, a monolithic ceramic capacitor having a good temperature characteristic and excellent reliability is achieved by adding a rare-earth oxide, MgO, and MnO to a main component represented by {Ba1-xCaxO}mTiO2 and limiting the molar ratio x between Ca and Ba, the molar ratio m of (Ba,Ca) to Ti, and the molar ratios α, β, and γ of the respective additive components to the main component to predetermined ranges.
Furthermore, in another conventional technology, a dielectric ceramic having a component represented by general formula {Ba1-xCax}mTiO3+α1BaO+α2CaO+βV2O5 and containing 0.2 to 5.0 parts by weight of a certain sintering additive per 100 parts by weight of a main component represented by (Ba1-xCax)mTiO3 has been disclosed
(Patent Document 2).
In Patent Document 2, a monolithic ceramic capacitor having a good temperature characteristic, a high isolating property, and excellent reliability is achieved by adding BaO, CaO, and V2O5 to the main component represented by {Ba1-xCax}mTiO3 and limiting the molar ratio x between Ca and Ba, the molar ratio m of (Ba,Ca) to Ti, and molar ratios α1, α2, and β of the respective additive components to the main component to predetermined ranges.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2000-58378
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2003-165768